Hydraulic drill collar retrieving mechanism



Jan. 19, 1960 F, LE BUS, SR 2,921,630

HYDRAULIC DRILL COLLAR RETRIEVING MECHANIISM Fly] Fg ATTOR Jan. 19, 1960 F. L. LE Bus, sR`4 HYDRAULIC DRILL` COLLR RETRIEVING MECHANISM 2 Sheets-Sheet 2 Filed Jan. 20, 1954 ATTRNS .mw

United States Patent C HYDRAULIC DRILL COLLAR RETRIEVING MECHANISM Franklin L. Le Bus, Sr., Longview, Tex., assignor to The Wash Overshot and Spear Engineers, Incorporated, Longview, Tex., a corporation of Texas Application `lanuary 2i), 1954, Serial No. 405,186

8 Claims. (Cl. 166-103) This invention relates to improvements in drill collar retrieving apparatuses, and more particularly, but not by wayof limitation, to improvements in the type of drill collar retrieving apparatuses which simultaneously hold and dislodge stuck drill collars. f

As it is well known in the art of drilling, the majority of oil wells drilled at the present time utilize the rotary drilling method. In this method, the drill string consists of a plurality of drill pipe joints secured in tandem relation with a varying number of drill collars depending in tandem relation from the drill pipe and having a drill bit on the lower end thereof. The entire drilling string is secured to a kelly at the surface, and in operation, is rotated by a rotary table surrounding the kelly to drill the well bore.

The drill collars are heavy, rigid, tubular members which are diflicult to bend. Therefore, when the drill bit is forced from a true vertical course by tilted geological formations or the like and make a crooked bore, the drill collars will rub against the side of the well bore and form an oit-set recess commonly called a keyseat. In a large percentage of oil wells, and particularly deep oil wells, the well bore will contain several of these key-seats. When the drill bit is being removed from such a well bore, the bit will become lodged in one of these key seats, since they are of smaller vdiameter than the well bore proper. The usual procedure is then to disconnect, and remove from the well bore, all of the drill pipe and a portion of the drill collars; leaving the drill bit and one or more drill collars lodged in the well bore.

The lodged drill collars and bit are usually removed by running a reamer on the end of a string of wash-over pipe down over the drill collars. The reamer reams out the key-seat and frees the drill bit; whereupon the drill bit and attached collars fall to the bottom of the well bore. It is then necessary to run another set of tools into the well bore and remove the drill bit and collars, which are usually damaged from the previous fall.

The present invention contemplates a novel drill collar retrieving apparatus adapted to recover the lodged drill bit and collars in one trip of tools in the well bore without damaging the drill bit or collars. The retrieving apparatus is carried in the wash-over string and engages the uppermost drill collar as the wash-over pipe is initially telescoped over the drill collars. A reamer on the wash-over pipe frees the drill bit and collars, and during the entire reaming operation, the drill collars are engaged by the retrieving device. Therefore, when the drill bit is dislodged, the drill collars and bit will be prevented from dropping to the bottom of the well bore. Subsequently, the wash-over string, with the drill bit and collars attached, may be removed from the well bore.

In the event the drill bit and collars cannot be removed, or it is not desired to remove them, the drill collars may be gently lowered to rest on the bottom of Itht-.well bore and the retrieving apparatus may be sepa- 2,921,630 Patented Jan. 19,Y 1960 Tice rated by circulating fluid or drilling mud pressure. The wash-over string may then be removed from the well bore; leaving the drill collars, bit, and a portion of the retrieving apparatus in the bottom of the well bore. At a later time, the drill collars and bit may be recovered from the bottom of the Well bore by other suitable tools.

An important object of this invention is to ream around lodged drill collars in a well bore k"while simultaneously holding the drill collars from downward movement.

YAnother object of this invention is to provide means for reaming out key-seats lodging drill collars in a Well bore and preventing downward movement of the drill collars when they become dislodged. l

Another object of this invention is to provide a mechanism for dislodging and recovering lodged drill collars in one operation of running tools in the well bore.

A further object of this invention is to provide a drill -collar retrieving mechanism in a wash-over pipe which may be disconnected by hydraulic pressure.

Another object of this invention is to provide a drill 'collar retriever apparatus in a wash-over pipe which may be disengaged without mechanically lowering disconnecting tools in an oil well bore.

Other objects and advantages of the invention will be evident from the following detailed description, read in conjunction with the accompanying drawings, which illustrate my invention.`

In the drawings: Figure 1 is a vertical sectional view of the upper por- -tion of my novel drill collar retrieving apparatus installed in a wash-over pipe.

Figure 2 is a continuation of Fig. 1 illustrating a lower portion of the drill collar retrieving apparatus.

Figure 3 is a continuation of Fig. 2 illustrating a still lower portion of the retrieving apparatus.

Figure 4 is a continuation of Fig. 3 showing the bottom portion of the retrievingl apparatus engaged with a Y drill collar.

Figure 5 is a vertical sectional view, partially in elevation, similar to Fig. 3 illustrating the initial step of separating'the retrieving apparatus. f

Figure 6 is another vertical sectional view illustrating the complete separation of the retrieving apparatus.

` Referring to the drawings in detail, and particularly Figs. l to 4, reference character 1 designates a string of wash-over pipe having a tubular reamer 2 (Fig. 4) on the lowerend thereof. The wash-over pipe 1 is suspended on the lower end of a string of drill pipe (not shown) which extends to the surface of the well bore in the well bore and which the reamer 2 is to dislodge when utilizing the present invention.

A novel drill collar retrieving mechanism, generally indicated at 4 and shown extending through Figs. 1 to 4,

`is inserted in the wash-over pipe 1 shortly above the reamer 2. The retrieving mechanism 4 comprises, in theY main, a tubular mandrel, generally indicated at 5 and extending from theV upper endthrough the major portion of the mechanism; a wash-over gripping or supportmg mechanism (Figs. 2V and 3), generally indicated at '6, for the purpose of slidably supporting the mandrel 5,

and a drillcollar engaging portion (Figs. Y3 'and-4), generally indicated at 7, at the lower end ofthe mechanism forV engaging the drill collar 3.

The mandrel 5 is concentrically` disposed in the washover pipe 1 and is constructed in several sections. The upper section 8 (Fig. l) is provided with an enlarged head portion 9 having a downwardly and inwardly tapered bore 10 therethrough. VA plurality of transverse apertures `11 extend through the walls of the section 8 slightly below the head 9, and a downwardly facing circumferential shoulder 12 is provided on the outer periphery of the section 8 below the apertures 11.

A tubular shaped orifice housing section 13 is threadedly secured to the lower end of the upper section 8 by a connecter member 14. An upwardly extending circumferential flange 15 is formed on the upper end of the connecting member 1d to receive and support a packing 4unit 16. The flange 15 retains the packing unit 16 in tight contact with the outer periphery of the member 8 and against the shoulder 12. The packing unit v16 provides a fluid seal between the mandrel section 8 and the inner periphery of the wash-over pipe 1 to prevent a downward -ftow of fluid around the mandrel at this point, as will be more fully hereinafter set forth.

The orice housing section 13 extends on downwardly from the section 8 and is threadedly secured at its lower end to another connecting member or collar 17. A tubular insert 1Sl is threaded into the collar 17 immediately below the housing section 13 and is retained in the collar 17 by the section 13. rl`he insertlS extends upwardly in the housing 13, and the inner surface thereof is tapered downwardly and inwardly at the upper end to form a seat 19. An orifice unit 2d is adapted to rest on the seat 19 and assist in the actuation of the. mandrel 5. However, the orifice unit Zit is utilized only after the drill collar 3 has been engaged and dislodged, and isnot present in the housing 13 at the beginning of the` retrieving operation. Therefore, the detailed description of the unit 20,. and a companion unit 21, will be deferred to a more appropriate place.

The collar 17 forms a threaded connection between the orilice housing section 13 and a lower tubular section 22 (Figs. l and 2) of the mandrel 5. In addition, the

collar 17 is externally threaded near its lower end 23 to 22 and has a plurality of transverse apertures 25 in the medial portion thereof for discharging circulating iuid,

as will be hereinafter set forth. A helical spring 26 surrounds the mandrel section 22 inwardly of the spring guide 24 and is anchored at its upper end to an adjusting nut 27 threadedly secured to the section 22 immediately below the collar 17.

In the normal operating position of the spring 26, its lower end is substantially even with the lower end of the spring guide 24. A plurality of circumferentially spaced vvertical slots 28 are provided in the lower end of the mandrel section 22 immediately above the threaded connection of the section 22 with a still lower tubular mandrel section 29. The section 29 extends concentrically through the supporting mechanism 6.

The supporting mechanism 6 comprises a tubular housing 30 having an inner diameter slightly larger than the outer diameter of the mandrel section 29, thereby providing a sliding t between these two elements. An extension 31 is threadedly secured to the upper end of the housing 30 and extends upwardly around the mandrel sections 29 and 22. The upper end of the extension 31 provides an anchor for the lower end of the spring 26. The spring 26 has suicient strength to support the mandrel 5 in the gripping mechanism 6 and continually urges the mandrel S in an upward direction.

A plurality of circumferentially spaced vertical slots 32 are provided in the extension 31 opposite the slots 2S in the mandrel section 22. The slots 32 are of greater length than the slots 28, and in cooperation with the slots 28, provide passageways for circulating Huid from the mandrel 5 into the annulus 33 between the extension 31 and the wash-over pipe 1. n

The lower end of the extension 31 forms a downwardly facing circumferential shoulder 34 to prevent upward movement of a slip shoe or head 3S. The slip shoe 35 surrounds the housing 39 and is keyed thereto by a key 36 to prevent rotation of the shoe 35 on housing 30. Downward movement of the shoe 35 is prevented by the key 36. A plurality of downwardly and inwardly tapered surfaces 37 are arranged in circumferentially spaced relation on the outer periphery of the shoe 3S to receive serrated slips 33. It will be apparent that the slips 38 will engage the wash-over pipe 1 upon downward movement of the shoe 35 and will be disengaged from the Washover pipe 1 upon upward movement.

Links 39 interconnect the slips 3d with a dog cage 40 through pin type connections 41 at each end of the links 39. The dog cage 4t) is tubular in construction and is secured to the outer periphery of the housing 30 by a key 42. The key 42 is loosely disposed in cooperating .slots 43 formed in the housing 3i) and dog cage 40 to provide a limited vertical movement of the dog cage 4G. A plurality of vertical slots 44 are provided in the outer periphery of the dog cage 4d to receive dog members 45. The dogs 45 are radially movable to frictionally engage the wash-over pipe i and are constantly urged in an outward direction by small helical springs 46. Transverse pins 47 are securedin the dog cage 40 at each end of each slot 44 and extend through slots 48 in the opposite ends of the dogs 45 to limit the outward movement of the dogs 4S.

The housing 30 extends downwardly below `the dog cage 4d and has a helical spring 49 thereon resting on a circumferential shoulder 50 on the housing. The spring 49 supports the dog cage 43 and assists in actuation of the slips 3S, as will be hereinafter set forth. Referring to Fig. 3, it will be noted that a counter-bore 5l is formed in the lower portion of the housing 30 and contains an expander head 52. The expander head 52 is threadedly secured to the lower end 53 of the mandrel section 29 and is loosely disposed in the counter-bore 51. A shoulder S4 is formed on the lower end 53 of the mandrel section 29 and is of greater diameter than the bore of the housing 3). Thus, the shoulder 54 will contact the upper end of the counter-bore 51 of housing 30 and limit the upward movement of the expander head S2. The expander head 52 has an upper portion 52a of smallest external diameter, and an intermediate portion 5S of external diameter larger than the smallest portion 52a, and a lower portion 56 of greatest external diameter en-, gageable with dogs 57 inserted in vertical slots 58 of the housing 30. The largest portion 56 of the expander head 52 engages the dogs 57 to maintain them in expanded position for locking the sleeve 59 of the drill collar engaging means 7 tothe housing 39. The dogs 57 are circumferentially spaced around the housing 3ft opposite the counter-bore 51, and are adapted to move radially in the slots 5S to engage in circumferentially spaced recesses (not shown) provided in the sleeve 59 of the drill collar engaging mechanism 7 as will be hereinafter set forth. An inwardly extending shoulder 60 is formed on the upper end of each dog 57 to cooperate with the expander head 52.

Additional vertical slots 61 are formed in the housing 30 below the dogs 57 to receive shear pins 62 extending inwardly from the sleeve 59. The shear pins 62 assist in supporting the drill collar engaging mechanism 7, particularly in the event the dogs 57 are not operating, to prevent inadvertent release of the mechanism 7. A bearing retaining ring 63 is secured in the sleeve 59 below the lower end 64 of the housing 30 by a plurality of bolts 65. The bearing retaining ring 63 rests upon a thrust bearing unit 66, which in turn is disposed on the upper end 67 of another tubular section 68 of the drill collar engaging mechanism 7.

The sleeve 59 is threadedly secured to the upper end 67 of the section 68 and thethreaded engagement i8 Vretained by a lock screw 69. A tubular insert 70 is threadedly secured in the upper end of the sleeve 59 above vthe dogs 57. The insert 70 extends downwardly in the sleeve 59 and prevents upward movement Vof a rubber vbumper ring 71 and a metal shock ring 72 disposed in the sleeve 59. The rings 71 and 72 are utilized to assist in the retraction of the dogs 57, as will be hereinafter set lforth, and the lower end 73 of the shock ring 72 is tapered upwardly and inwardly to facilitate actuation of the dogs 57. A circumferential shoulder 74 is formed on the inner peripheryof the sleeve 59 to prevent downward movement of the rings 71 and 72 `relative to the sleeve 59.

Referring to Fig. 4, it will be noted that the tubular `section 68 ofthe drill collar engaging mechanism 7 screws Ainto a lower tubular member 75 which extends on down Yin the wash-over pipe 1 and terminates in a head or slip shoe 76. A sleeve 77 is threadedly secured around the member 75 adjacent the upper end thereof and extends downwardly around the member 75 to form a guide for a helical spring 78. The spring 78 surrounds the memlber 75 and is anchored at its upper end to a downwardly facing shoulder 79 on the member 75. The lower end of the spring 78 restson a floating-ring 80 which is also lspaced vertical slots 85 formed in the outer periphery of the head 76. Bolts 86 are secured in the lower portion of each slot 85, thereby providing stops to limit the downward movement of the slips 84. The slots 85 are tapered downwardly and outwardly to force the slips 84 into engagement with the threaded box 87 of the drill collar 3 as will be hereinafter set forth.

Operation To recover the lodged drill collar 3, the wash-over pipe 1, with the reamer 2 attached to the lower end thereof and the retrieving apparatus 4 disposed above the reamer 2, is lowered in the well bore. When the apparatus 4 is inserted in the wash-over pipe 1, the friction dogs 45 (Fig. 2) engage the inner periphery of the wash-over F pipe 1 and support the entire apparatus 4. Furthermore, -'the spring 26 (Fig. 2) will exert an'upward force on the mandrel 5 to retain the `expander head 52 in its upper- `most position as shown in Fig. 3 with the flange 54 in con- 1 tact with the upper end of the counter-bore 51. Thus, the f largest portion 56 of the expander head 52'will be in contact with the inner periphery of the dogs 57 to retain them in engagement withv the sleeve 59 and support the drill collar engaging mechanism 7. As previously noted, the

orifice units 20 and 21 are not present in the orifice housing section 13 of the mandrel 5 at this time.

The entire wash-over string, comprising the wash-over pipe 1 and drill pipe interconnected by a slip joint, are

lowered and rotated in the well bore to provide a reaming action of the reamer 2 and remove all key-seats existing Ain the well bore. Simultaneously, drilling mud, or circulating fluid, is pumped downwardly through the washover string to remove cuttings produced by the reamer 2 and wash the cuttings upwardly in therannulus between the wash-over string and well bore. The iluid enters the mandrel through the tapered bore 10 (Fig. l). A

portion of the lluid passes outwardly through the apertures 1l and downwardly around the head 9 to force the packing unit 16 outwardly and form a seal with the wash-over pipe 1. The remainder of the fluid ilows on down through the sections 8, 13 and 22 of the mandrel 5. It will be noted that the bore 29a of the mandrel section 29 is smaller than the bore of the section 22,.there fore aportion of thelluid is diverted-through the slots 28 and 32`into the annulus 33. The diverted tluid flows downwardly in the annulus 33 around thesupporting mechanism 6 and drill collar 'engaging mechanism 7 Ato ilush out the reamer 2. The remainder of the lluid flows on down through section 29, expander head 52, section 68 and member 75 into the drill collar 3 to assist in dislodging the drill collar 3. y

As the wash-over pipe 1 and reamer 2 are telescoped over the 'drill collar 3, the head 76 and slips 84 enter the box 87 of the drill collar 3. The rotative motion of the entire apparatus 4, in combination with downward force of the spring 78, threads the slips 84 in the box 87. When the slips 84 engage the box 87, the entire apparatus 4 stops moving in a downward direction, but the washover pipe 1 continues moving in a downward direction and vrotates to continue the reaming action around the drill collar 3. It will then be noted that the wash-over pipe 1 will exert a downward force on the friction dogs to assure a disengagement of the slips 38.

The rotative and downward movement of the wash-over string is continued until the drill collar 3 is dislodged, whereupon the drill collar 3 will tend to fall to the bottom Yof the well bore. The downward force caused by the initial downward movement of the drill collar 3 is transmitted through the slips 84, head 76, member 75, section 68, sleeve 59, dogs 57 and housing 30 to the slip shoe 35. Since the friction dogs 45 will tend to remain stationary within the wash-over pipe 1, and are urged upwardly by the spring 49, the shoe 35 will move downward through the slips 38 and expand them into engagement with the wash-over pipe 1. When the slips 38 become engaged, the drill collar 3 is effectively secured to the wash-over pipe 1 and will be prevented from further falling. Y

The entire wash-over string, with the drill collar 3 attached, may then be removed from the well bore. However, if it is not deemed expedient to remove the drill i collar 3 with the apparatus 4, the wash-over string may cally through use of the orice unit 20 (Fig. l).

be lowered to place the drill collar 3 on the bottom of the well bore; whereupon the retriever 4 may be separated to permit separate removal of the wash-over string.

Separation of the retriever 4 is accomplished hydrauli- The unit 20 comprises a tubular plug 91 having a lower tapered `end 92 constructed to rest upon the seat 19. A sealing ring 93 is placed on the tapered portion 92 to provide a seal with the seat 19 and prohibit flow of circulating fluid around the plug 91. The inner bore of the plug 91 is partially threaded to receive a threaded bushing 94 and a tubular extension 95. A frangible solid disc 96 may be secured in the plug 91 by the bushing 94, however, the `,disc 96 is not ordinarily used, as will be shown hereinafter. The upperinner end of the extension is tapered inwardly and downwardly to form a seat 97 for the vorifice unit 21. The remaining length of the inner bore of the insert 95 is similarly tapered, but to a much lesser extent, to receive an orice plate 98. It will be apparent that the o rice plate 9-8 is wedged into the extension 95, and that the plate 98 will restrict the ow of circulating fluid through the mandrel 5.

When it is desired to separate the retriever 4, the orifice unit 20 is pumped down through the wash-over string by the circulating fluid and comes to rest on the seat Y19. Continued pumping of the circulating fluid causes an increase of uid pressure above the orifice plate 98 due to its decreased opening. The pressure on the mandrel 5 is increased until enough force is built up to overcome the action of the spring 26; whereupon the mandrel 5 moves downwardly through the supporting mechanism 6. As shown in Fig. 5, the expander head 52 is therefore moved downwardly to move the portion 55 below the shoulders 60 of the dogs 57. The dogs 57 are then free to move inwardly out of engagement with the sleeve 59 and free the drill collar engaging mechanism 7.

After the expander head 52 is'. moved down, an upward 7 pull is exerted on the wash-over string. The dogs 57, being released, will exert no appreciable force on the sleeve 59, therefore the housing 30 will move upwardly through the sleeve 59. Furthermore, as the housing 30 is being moved up through the sleeve 59, the tapered end 73 of the shock ring 72 will contact the dogs 57 and move them inwardly into the counter-bore 51 in Contact with the head 52. The force required to raise the washover string will be sufficient to shear off the pins-62 (the only remaining attachment between the holding mechanism 6 and drill collar engaging mechanism 7) Yand free the housing 30 from the sleeve 59 as shown in Fig. 6. The wash-over string is then free for removal from the well bore; leaving the drill collar engaging mechanism 7 attached to the drill collar 3 at the bottom of the well bore. Other recovery tools may then be inserted in the well bore for recovering the drill collar 3.

The circulating fluid will harden around the reamer 2 at times and restrict the iiow through the retriever 4. When such a condition occurs, it may be impossible, or at least impracticable, to build up enough pressure on the 'mandrel 5 to compress the spring 26 by using only the orifice plate Sid. In this event, the frangible disc 96 may be secured in the plug 91. The disc'96 will prohibitV the flow of fluid through the mandrel until an appreciable pressure is built up above the orifice unit to compress the spring 26; whereupon the disc '96 will rupture and permit further flow of fluid through the retriever 4 to prevent hardening of the fluid therein.

A similar orifice unit 21, having an orltice plate 99 and frangible disc 1G() therein, may be pumped down on the seat 97 if additional restriction in the mandrel 5 (and hence increased pressure for compressing the spring Z6) is desired. The oriiice plate 99 is provided with a smaller orifice than the plate 98 to further reduce the ow of fluid through the mandrel 5.

From the foregoing, it is apparent that the present in- Vention provides a novel drill collar retrieving` apparatus for simultaneously holding and dislodging drill 'collars stuck in a well bore, whereby the drill collars -will not fail and be damaged. The drill collars may be dislodged and removed with one trip of tools in the well bore. Furthermore, the retrieving apparatus may be disconnected or separated from the drill collars by hydraulic pressure and without mechanically lowering tools in the Well bore.

Changes may be made in the combination and arrangement of parts as heretofore set forth in the specification and shown in the drawings, it being understood that any modification in the precise embodiment of the invention may oe made within the scope of the following claims without departing from the spirit oi the invention.

I claim:

l. An apparatus for retrieving one or more drill collars lodged in a well bore, comprising a wash-over pipe string of a size to enter the well bore and telescope over the drill collar, a reamer on the lower end of the wash-over pipe string to dislodge the drill collar, a tubular housing in the wash-over pipe string, dogs reciprocally carried by Vthe housing and frictionally engaging the wash-over vpipe string, a slip shoe on the housing, slips on the slip shoe connected to the dogs, mandrel means extending through the housing and slidably supported therein, said mandrel means being responsive to iiuid pressure for movement in one direction through the housing, spring means provided in the housing for urging the mandrel in an -upward direction in relation to the housing and supporting the mandrel in an upper position, and drill collar engaging means releasably secured to the housing, a second set of dog means carried by the housing means, and expander head means provided on the mandrel for actuation of the second dog means for securing the drill collar engaging means to the housing in one position of the mandrel means and separated Yfrom the housing in a second position of the mandrel means.

2. An apparatus for retrieving 4one ormore drill collars lodged in a well bore, .comprising a wash-overipipe string of a size to enter the well bore and telescope over a drill collar, a vreamer on .the lower end ofthe wash-over pipe string to dislodge the drill collar, ,a tubular housing lin the lower portionof the Ywash-.over pipe string, wash-over pipe gripping meansA mounted on the tubular housing, tubular mandrel means .extendingV through the housing and slidable therein in one direction `in response to fluid pressures, spring :means on the housing for urging lthe mandrel means upward relative to the housing and supporting the mandrel means in .its upper position, drill collar engaging means, dogs carried by rthe housing for securing the drill collar yengaging means to vthe housing, expander means provided on the .lower end .of .the mandrel whereby in the upper position of the mandrel said .eX- pander means locks said last mentioned dogs in an expanded position for locking the drill collar .engaging means to the .tubular housing, said -last mentioned dogs being operable by the 'tubular housing for releasing the drill collar engaging means :Upon downward movement of the expander means, and means for applying fluid pressure on the mandrel means tomOVe the mandrel means in a downward direction through the 4housing and releasing the drill collar engaging means.

3. A drill collar retrieving vapparatus -for use -in a washover pipe having fluid iiiowing downwardly therethrough, comprising a tubular housing vin `thewashover pipe, dogs reciprocally carried by the housing Aand frictionally engaging the wash-over pipe, a Yslip shoe on 4the housing, slips on the slip shoe operable by Vthe dogs to engage the wash-over pipe upon downward movement of the housing in the wash-over pipe, tubular mandrel means extending through the housing and Vreciprocal Ytherein in response to opposing ,mechanical pressure Yand uid pressure, spring means in the housing yieldablysu-pporting the mandrel means, an expander head on lthe mandrel means, drill collar engaging means, a ,second set of dogs on the housing for releasably ,securing the drill collar engaging means to the housing, said second set of dogs being operable by the expander head for radially expanding the second dogs for securing the .drill ,collar means to the housing, Vand means for varying the uid pressure applied to the mandrel means, whereby `the expander head may be moved .downwardly to permit movement of the second set of .dogs in order to release the drill collar .engaging means.V

4. A drill collar retrieving apparatus lfor 'use in a wash-over pipe having fluid flowing Vdownwardly therethrough, comprising a tubular housing inthe wash-over pipe, dogs reciprocally carried 4by the housing and frictionally engaging the wash-,over .pipe, `a slip shoe on the housing, slips .on lthe slip shoe .operable-by the rdogs to engage the wash-.over pipe .upon downward movement of the housing in the Wash-.over pipe, tubular mandrel means extending ,through the housing and reciprocal therein in response to opposing mechanical .and fluid pressure, spring means onthe housingrurging the mandrel means upwardly with respect to the housing and-yieldably supporting the mandrel means in its upper position, .an expander head on .the mandrel means, drill collar .engaging means, a second set Vof `dogs on the housing for releasably securing the .drill .collar engaging means vtothe housing, said second set .of .dogs :being operable by the expanderhead in `the lupper position of the mandrel means for 'locking the dogs .in .an expanded position for locking the Adrill .collar engaging means to the housing, a packing unit around .the mandrel in .Contact with the wash-over pipe, an Vorifice unit insertable in the tubular mandrel means adjacent the packing unit for reducing the inner diameter :of .the imflldrtl .imens and increasing the duid .pressure .on the mandrel means, whereby the expander head :may be Amoved:.down.Wardly to permit movement of the ysecond set .of `Clogs in ordel to release the drillcollar engaging means.

5, ,apparatus for :retrieving one ,or :more drill eollars lodged in a Well bore, comprising a wash-over pipe string of a size to enter the well bore and telescope over a drill collar, a reamer on the lower end of the wash-over pipe string to dislodge the drill collar, a holding assembly comprising a wash-over pipe gripping and drill collar supporting means in the lower portion of the wash-over pipe string, mandrel means extending through the wash-over pipe supported by said supporting means and movable relative thereto, 4a longitudinal bore in the mandrel having a portion thereof restricted, said mandrel responsive to flow of iluid under pressure to move -the mandrel in one direction relative to the holding assembly, spring means provided in the holding assembly urging the mandrel n a direction opposite to said first mentioned direction, drill collar engaging means releasably securable to the supporting means, dog means carried by the supporting means, and expander means provided in the mandrel means for actuating the dog means for securing the drill collar engaging means to the supporting means when said mandrel means is moved in said opposite direction, said expander means moved downwardly by the mandrel means for releasing the drill collar engaging means from the supporting means upon movement of the mandrel means in said first mentioned direction.

6. An apparatus for retrieving one or more drill collars lodged in a well bore, comprising a Wash-over pipe string of a size to enter the well bore and telescope over the drill collar, a reamer on the lower end of the washover pipe to dislodge the drill collar, a holding assembly comprising a wash-over pipe gripping and drill collar supporting means in the lower portion of the Wash-over pipe string, said gripping means comprising a plurality of friction dogs engaging the wash-over pipe string, a slip shoe connected to the friction dogs, a plurality of slips on the slip shoe for engaging the wash-over pipe string upon movement of the slip shoe downwardly therein, mandrel means extending through the Washover pipe supported by said supporting means and movable relative thereto, a longitudinal bore in the mandrel means having a portion thereof restricted, said mandrel means being responsive to flow of fluid under pressure to move the mandrel in one direction relative to the holding assembly, spring means provided in the holding assembly urging the mandrel in a direction opposite to said rst mentioned direction, drill collar engaging means releasably securable to the supporting means, dog means carried by the supporting means, and expander means provided in the mandrel means for actuating the dog means for securing the drill collar engaging means to the supporting means when said mandrel means is moved in said opposite direction, said expander means moved downwardly by the mandrel means for releasing 10 the drill collar engaging means from the supporting means upon movement of the mandrel means in the said rst mentioned direction.

7. An apparatus for retrieving one or more drill collars lodged in a well bore, comprising a wash-over pipe string of a size to enter the Well bore and telescope over a drill collar, a reamer on the lower end of the wash-over pipe string to dislodge the drill collar, a holding assembly comprising a wash-over pipe gripping and drill collar supporting means in -the lower portion of the wash-over pipe string, mandrel means extending through the wash-over pipe supported by said supporting` means and movable relative thereto, a longitudinal bore in the mandrel having a portion thereof restricted, said mandrel responsive to flow of fluid under pressure t0 move the mandrel in one direction relative to the holding assembly, spring means provided in lthe holding assembly urging the mandrel in a direction opposite to said rst mentioned direction, drill collar engaging means carried by the supporting means, expander means provided on the mandrel m'eans, and means carried by the supporting means and actuated by the expander means upon movement of the mandrel means in said opposite direction for releasably securing the drill collar engaging means to the supporting means.

8. An apparatus for retrieving one or more drill collars lodged in a well bore, comprising a wash-over pipe string, a rearner on the lower end of the washover pipe string to dislodge the drill collar, a holding assembly comprising a wash-over pipe gripping and drill collar supporting means in the wash-over pipe string, a mandrel extending through the wash-over pipe and supported by the supporting means and movable relative thereto, a longitudinal bore in the mandrel having a portion thereof restricted, said mandrel being responsive to flow of lluid under pressure to move the mandrel in one direction relative to the holding assembly, spring means provided in the holding assembly urging the mandrel in a direction opposite said lrst mentioned direction, drill collar engaging means carried by the supporting means, expander means provided on the mandrel, and dogs carried by the supporting means and actuated "by the expander means upon movement by the mandrel for alternately securing the drill collar engaging means to the supporting means and releasing the drill collar e11- gaging means from the supporting means.

References Cited in the le of this patent UNITED STATES PATENTS 2,179,033 Cashion et al. Nov. 7, 1939 2,449,841 Claypool et al. Sept. 21, 1948 2,647,008 Stewart July 28, 1953 

